1. The Field of the Invention
The present invention relates generally to telecommunications systems. More particularly, the present invention relates to an eye safety shutdown mechanism in a laser transmitter with compensation for transient conditions such as start-up conditions.
2. Background and Relevant Art
Fiber optic technology is increasingly employed as a method by which information can be reliably transmitted via a communications network. Networks employing fiber optic technology are known as optical communications networks, and are marked by high bandwidth and reliable, high-speed data transmission.
Optical communications networks employ optical transceivers in transmitting information via the network from a transmission node to a reception node. An optical transceiver at the transmission node receives an electrical signal from a network device, such as a computer, and converts the electrical signal via a laser to an optical signal. The optical signal can then be emitted by the transceiver and transmitted in a fiber optic cable via the optical network. The optical signal is then received by a reception node of the network. Once received by the reception node, the optical signal is fed to another optical transceiver for conversion via a photodetector into electrical signals for forwarding or further processing.
As the optical communications network employs optics as a mechanism for data transfer, it is important that the optical signal presents no health hazard to bystanders. For example, if the optical cable were to become unplugged, the optical signal is no longer contained and may be freely emitted into the environment. It is possible that the emitted optical signal may be received by a human eye. If the intensity of the optical signal is too high, this could harm the human eye. Accordingly, for safety purposes, the optical intensity of the laser is kept low such that eye safety is assured even should the optical cable become unplugged. Conventional optical transceivers thus have eye safety mechanisms that shut down the optical transceiver should the optical intensity become too great.
While this promotes eye safety, there can be transient conditions during which the optical intensity falls outside of a desirable operating range. However, in many of such transient conditions, there is no significant safety hazard. For example, the optical intensity may only be large for a small time period not significant enough to cause harm. Furthermore, startup conditions may cause the optical signal to actually be below the desirable operating range thereby presenting no eye safety hazard. Shutting down the optical transceiver under such conditions is too extreme since the optical transceiver is rendered inoperative despite there being no real eye safety hazard.
While some conventional eye safety mechanisms provide for some level of assurance that a shut down of the transceiver will not occur unless there is a safety hazard, what would be advantageous are mechanisms that further increase this level of assurance. It would further be desirable if the eye safety mechanism could be integrated even without the assistance of an external controller.